Good occlusal practice in simple restorative dentistry

Fabrication of Definitive Cast for Complete Mouth Rehabilitation by Using Resin-Transfer Coping

One of the most challenging steps in dentistry is taking final impressions for full mouth rehabilitation of a dentate patient. Final impressions should include the necessary details needed to fabricate a definitive cast. This cast will be used to construct indirect restorations in the laboratory. Besides all the improvement of impression materials and systems used for taking final impressions, the intraoral cavity is a challenging environment and there are some cases that prevent clinicians from recording the needed details in a single final impression. The objective of this case report is to describe a technique for fabrication of a definitive cast for a full mouth rehabilitation case by using resin-transfer coping impression technique. This technique is used as an alternative option for cases that prevent the clinician from capturing all the needed details in a single full-arch final impression.

A dental revolution: The association between occlusion and chewing behaviour

Dentistry is confronted with the functional and aesthetic consequences that result from an increased prevalence of misaligned and discrepant dental occlusal relations in modern industrialised societies. Previous studies have indicated that a reduction in jaw size in response to softer and more heavily processed foods during and following the Industrial Revolution (1,700 CE to present) was an important factor in increased levels of poor dental occlusion. The functional demands placed on the masticatory system play a crucial role in jaw ontogenetic development; however, the way in which chewing behaviours changed in response to the consumption of softer foods during this period remains poorly understood. Here we show that eating more heavily processed food has radically transformed occlusal power stroke kinematics. Results of virtual 3D analysis of the dental macrowear patterns of molars in 104 individuals dating to the Industrial Revolution (1,700-1,900 CE), and 130 of their medieval and early post-medieval antecedents (1,100-1,700 CE) revealed changes in masticatory behaviour that occurred during the early stages of the transition towards eating more heavily processed foods. The industrial-era groups examined chewed with a reduced transverse component of jaw movement. These results show a diminished sequence of occlusal contacts indicating that a dental revolution has taken place in modern times, involving a dramatic shift in the way in which teeth occlude and wear during mastication. Molar macrowear suggests a close connection between progressive changes in chewing since the industrialization of food production and an increase in the prevalence of poor dental occlusion in modern societies.

Occlusion: is there a third way? A discussion paper

This paper does not set out to describe the reasons why a new concept of dental care should be deemed as acceptable and recognised as mainstream. Rather, the starting point of this paper is the belief that some dentists who are increasing the overall vertical dimension for worn dentition patients are not using the protocols of the traditional 're-organised approach'. If adhesive direct restorations are used, there seems to be anecdotal indication that despite not restoring in the terminal hinge axis, it can have a successful outcome.So, while not criticising this approach simply because it does not follow orthodoxy, the paper has two objectives. It hopes to stimulate some debate and research on this subject. Furthermore, by suggesting some parameters for what might be considered a new approach, it aims to improve patient outcome.

Comparison between Occlusal Errors of Single Posterior Crowns Adjusted Using Patient Specific Motion or Conventional Methods

Recently, digital technology has been used in dentistry to enhance accuracy and to reduce operative time. Due to advances in digital technology, the integration of individual mandibular motion into the mapping of the occlusal surface is being attempted. The Patient Specific Motion (PSM) is one such method. However, it is not clear whether the occlusal design that is adjusted using PSM could clinically show reduced occlusal error compared to conventional methods based on static occlusion. In this clinical comparative study including fifteen patients with a single posterior zirconia crown treatment, the occlusal surface after a clinical adjustment was compared to no adjustment (NA; design based on static occlusion), PSM (adjusted using PSM), and adjustment using a semi-adjustable articulator (SA) for the assessment of occlusal error. The root mean square (RMS; μm), average deviation value (±AVG; μm), and proportion inside the tolerance (in Tol; %) were calculated using the entire, subdivided occlusal surface and the out of tolerance area. Using a one-way ANOVA, the RMS and +AVG from the out of tolerance area showed a statistical difference between PSM (202.3 ± 39.8 for RMS, 173.1 ± 31.3 for +AVG) and NA (257.0 ± 73.9 for RMS, 210.9 ± 48.6 for +AVG). For the entire and subdivided occlusal surfaces, there were no significant differences. In the color-coded map analysis, PSM demonstrated a reduced occlusal error compared to NA. In conclusion, adjustment occlusal design using PSM is a simple and effective method for reducing occlusal errors that are difficult to identify in a current computer-aided design (CAD) workflow with static occlusion.

Interocclusal Records in Fixed Prosthodontics

An accurate interocclusal record is essential for the successful delivery of fixed prosthodontic restorations. There are various materials and techniques used to obtain an interocclusal record in order to facilitate mounting of the dental casts on an articulator. The interocclusal record describes the vertical and horizontal relationship of the maxillary and mandibular teeth. In circumstances where the vertical relationship is not supported through a tripod of widely spaced opposing contacts, the interocclusal record will be needed to restore this vertical support to prevent inaccurate mounting. The clinician should understand when an interocclusal record is required and have an awareness of the different materials and techniques available to record an interocclusal registration.

Occlusion and Disocclusion Time Changes in Single Unit Crowns Designed by Functional Generated Path Technique: A Randomised Clinical Trial

Although it is believed that implementation of the functional generated path (FGP) technique can facilitate occlusal surface design for restorations, it has not been objectively compared in situ with the conventional fabrication yet. Therefore, in the present study, a single-blind crossover clinical trial was conducted using T-scan to compare changes in occlusion time (OT) and disocclusion time (DT) of single posterior artificial crowns designed differently using FGP technique (FGP), average-value FGP technique (AVR) and conventional fabrication (CON). Each of the 10 participants took part in the study tried three artificial crowns in different sequences according to a computer generated randomization list. The results objectively revealed that changes in OT and DT were significantly smaller for FGP than CON (P < 0.05) and considerably smaller for AVR than CON, respectively. The subjective feedback and the occlusal adjusting time were better and shorter for FGP and AVR than CON (P < 0.05). No harm to the participants occurred. Overall, FGP is an efficient technique showing more physiological harmonious relationship with the articulating system.

Bulk dentine replacement versus incrementally placed resin composite: A randomised controlled clinical trial

OBJECTIVE

This randomized controlled clinical trial compared two techniques and materials for restoring carious teeth-Bulk dentine replacement versus incremental placement of a hybrid posterior resin composite material in terms of patient comfort (post operative sensitivity and tenderness on biting).

MATERIAL AND METHODS

Seventy-two carious teeth were randomized to one of two treatment groups: Group A-were restored with a bulk dentine replacement material or Group B-restored with incrementally placed hybrid composite. Patients were followed up by way of a structured phone call at day 2 and day 7 post-operatively. Patients reporting discomfort at day 7 were subsequently followed up on days 14, and 30.

RESULTS

All patients were followed up. At day 2, 18/72 restored teeth had post-operative sensitivity; this figure fell to 10/72 at day 7. A Chi squared test revealed that at day 2 a greater level of sensitivity was reported by patients in Group A (P=0.029). However, at day 7 there was no statistically significant difference between the two groups in terms of sensitivity (P=0.453). 8/72 and 6 /72 teeth had tenderness to biting at days 2 and 7 respectively. A Chi squared test revealed no statistically significant difference between the two groups in terms of tenderness on biting at any time period (P=0.722). Interestingly, Class I cavities were found to be more tender on biting than Class II cavities. At day 30 2/72 teeth exhibited sensitivity and none of the teeth exhibiting tenderness on biting.

CONCLUSION

At day 7 there was no significant difference between the two groups in terms of postoperative sensitivity and tenderness on biting.

Combination of 2 three point articulators for preclinical work demonstration of teeth arrangement and anatomical landmarks

The combination of 2 three point articulators was done to visualize and appreciate the various teeth setting principles and anatomical landmarks both in occlusion and out of occlusion. In other words this technique would give a simultaneous image of the various teeth arrangement principles at a glance. The various teeth arrangement principles highlighted in this article would be the following: individual tooth arrangement principles of anterior and posterior teeth, arch form, midline, incisive papilla, retromolar pad, overjet and overbite.

Establishing better biological models to understand occlusion. I: TM joint anatomic relationships

Belief in and rejection of a relationship of occlusion and temporomandibular joint (TMJ) condyle-fossa position with normal and abnormal function are still contentious issues. Clinical opinions can be strong, but support in most published data (mostly univariate) is problematic. Distribution overlap, low sensitivity and specificity are a common basis to reject any useful prediction value. Notwithstanding, a relationship of form with function is a basic tenet of biology. These are multifactor problems, but the questions mostly have not been analysed as such. This review moves the question forward by focusing on TM joint anatomic organisation as the multifactor system it is expected to be in a closed system like a synovial joint. Multifactor analysis allows the data to speak for itself and reduces bias. Classification tree analysis revealed useful prediction values and usable clinical models which are illustrated, backed up by stepwise logistic regression. Explained variance, R(2), predicting normals from pooled TMJ patients was 32·6%, sensitivity 67·9%, specificity 85·7%; 37% versus disc displacement with reduction; and 28·8% versus disc displacement without reduction. Significant osseous organisational differences between TM joints with clicking and locking suggest that this is not necessarily a single disease continuum. However, a subset of joints with clicking contained characteristics of joints with locking that might contribute to symptom progression versus resistance. Moderately strong models confirm there is a relationship between TMJ osseous organisation and function, but it should not be overstated. More than one model of normals and of TM derangement organisation is revealed. The implications to clinical decision-making are discussed.

The quality of dental casts used in crown and bridgework

OBJECTIVE

To assess the quality of dental casts used in crown and bridge construction.

DESIGN

Observational cross-sectional study of dental casts.

SETTING

Commercial dental laboratories and a university dental hospital laboratory in the UK.

MATERIALS AND METHODS

A sample (n = 150) of working and opposing casts used for crown and bridgework prescribed by general dental practices and a dental hospital were sampled from two commercial dental laboratories and an 'on-site' university dental hospital laboratory respectively. A simple '3 point' assessment scale of quality (good, fair and poor) was used to categorise the casts depending on the clarity of reproduction of soft and hard tissues.

RESULTS

The quality of opposing casts used for articulation purposes was significantly better (P<0.001) than that of the working casts. In addition it was found that for working casts the quality in the preparation area(s) was significantly better (p<0.001) than that in areas remote from preparation(s) in the same arch. In general, the quality of casts in the incisal or occlusal surfaces was better than the buccal and lingual surfaces.

CONCLUSIONS

This study has demonstrated that variation exists in the quality of casts used in crown and bridgework, specifically those used in the construction of indirect restorations and also those used for articulation purposes. This study highlights the need for clinicians to exercise continued vigilance with crown and bridge impressions, and casts, particularly in areas away from the prepared teeth.

Inter- and intra-operator reliability of the recording of occlusal contacts using 'occlusal sketch' acetate technique

OBJECTIVES

To develop a simple way of recording occlusal contacts with proven inter- and intra-operator reliability.

SETTING

Clinical skills laboratory in the University Dental Hospital of Manchester.

MATERIALS AND METHODS

The marked static occlusal contacts of 20 sets of models were recorded in a pseudo-clinical situation, by three dentists and in addition by one dentist on two occasions using a schematic representation of the dental arch - the 'occlusal sketch'.

RESULTS

The median of Kappa agreement for inter- and intra-operator reliability was almost perfect.

CONCLUSIONS

The occlusal sketch is a simple, inexpensive and easy way of recording the results of an occlusal examination using marking papers.